1. Field of the Invention
The present invention relates to a capsule with improved disintegration comprising low-substituted cellulose ether that is mainly used for food and pharmaceutical products and to a method for preparing the same.
2. Description of the Related Art
Generally, a shell of a hard or soft capsule comprises a water-soluble shell-forming component such as gelatin, agar, carrageenan, hydroxypropylmethylcellulose and the like. And a hard capsule is prepared, for example, by filling a content into a hard capsule shell formed by adhering an aqueous solution of gelatin onto a mold pin and drying the solution.
On the other hand, a soft capsule is prepared, for example, by encapsulating a content by a soft capsule shell that are obtained by forming a gel from a shell base substrate comprising gelatin, water and a plasticizer.
However, the conventional shell for the capsule described above has the following problems:
(1) Because eicosapentanoic acid (hereafter referred to as “EPA”), docosahexaenoic acid (hereafter referred to as “DHA”), 3-carotene or the like, which is believed to be generally effective for the prevention of lifestyle diseases and the like, has many double bonds within the molecule, it is very easily oxidizable substance. Furthermore, because the substance has unpleasant taste and odor, it cannot be generally admixed to food as it is. Consequently, the substance is ordinarily used as health food sealed in a soft capsule. A method of adding the substance to food after sealing in a soft capsule is widely known (Japanese Patent Application Unexamined Publication No. 60-102138/1985, Japanese Patent Application Unexamined Publication No. 60-66935/1985, and Japanese Patent Application Unexamined Publication Nos. 2-203741/1990 and 5-65222/1993). However, although the methods can veil the unpleasant taste and odor, an oxidation of content cannot be completely prevented, so that the peroxide value increases as time passes, and the content turns yellow.
(2) Because the capsule used in pharmaceutical products or health food is generally required to have good intragastric dissolution after intake and the content's efficacy is displayed quickly, the improvement of the dissolution of a capsule has been an important problem to be solved. But nevertheless, water-soluble polymers that are soluble in water but do not disintegrate and tend to form a thick gel film are presently used for the capsule base substrate.